Impact-modified thermoplastic resin blends that include a polyester resin, a polycarbonate resin and a glycidyl ester impact modifier are known, see, e.g., U.S. Pat. Nos. 5,112,913 and 5,369,154, and have been used to mold articles, e.g., automotive components such as mirror housings and cowl vent grilles, wherein a glossy, defect-free surface appearance is of extreme importance.
A polymer blend comprising a polyalkylene terephthalate, an organopolysiloxane-polycarbonate block copolymer, and a halogenated copolycarbonate having improved impact, heat distortion and flame retardant properties is described in U.S. Pat. No. 4,155,898 to Bopp.
U.S. Pat. No. 4,794,141 to Winfried et al. relates to molding compositions containing polydiorganosiloxane/polycarbonate block copolymers, elastomeric polymers an, if appropriate, polyalkylene terephththalates. The elastomeric polymer is described as a hydrogenated block copolymer of a vinyl aromatic monomer and a conjugated diene.
U.S. Pat. No. 4,994,532 to Hawkins et al. describes functionalized polydimethylsiloxane fluids which react with polycarbonate in the melt to form polydimethylsiloxane/polycarbonate block copolymers. The resultant copolymers are described as transparent and show improved flow.
U.S. Pat. No. 5,026,791 to Hawkins et al. relates to an aromatic carbonate polymer having a siloxane unit in the backbone of the polymer.
U.S. Pat. Nos. 4,161,498 and 4,155,898, both to Bopp, and U.S. Pat. No. 4,161,469 to LeGrand et al. describe polyalkylene terephthalate resin and an organopolysiloxane-poly-carbonate block copolymer having impact and heat distortion properties.
While articles molded from known impact-modified polyester resin/polycarbonate resin blends provide, e.g., good impact performance, the weatherability of the such articles has been found to be deficient in some applications, i.e., it is desired to retain the impact resistance after long term exposure UV radiation, especially low temperature impact resistance. Hence, it is desirable to provide a molding composition having a combination of flame resistance, impact resistance with enhanced weatherability.